A. Field of the Invention
This invention relates to a telephone control interface system for use with digital telephones using a bus protocol which is coupled to programmable computer control.
B. Related Art
It is known in the art to provide a digital telephone with a general option protocol that enables a broad variety of options to be interchangeably connected to the telephone by way of common bus (the "option bus"), wherein internal telephone signals can be monitored and processed without the need for individual corresponding conductors. Such an option bus is present, for example, in the ROLMphone 600 models. The Option Bus provides a method and apparatus for connecting remote options to a digital telephone base. The method provides physical and communications protocols for connections and provides a flexible control scheme which can be as simple or elaborate as a given option requires.
The ROLMphone 600 includes an option bay connection, having a hierarchical control protocol to a digital telephone and makes available several types of information, including local analog audio, analog voice, digital voice, digital data and telephone control streams.
One of the options available for the ROLMphone 600 is a Data Communications Option (DCO). The DCO connects to the option bus and uses the available telephone control stream. Access to this control stream is via an applications programming interface (API) which interprets and manipulates the telephone control stream and presents the information in a different protocol and format to a programmable computing device such as a personal computer.
The API interface is useful because it provides an abstraction of telephony control that is more straightforward to a programmer than the actual telephone control protocol used in the telephone. Consequently, however, the DCO does not always present to the programmable computing device a detailed and accurate picture of what is happening within the telephone. In addition, the DCO may report information that is moving within the telephone, but in many instances does not provide a method to alter or altogether stop the flow of control information within the telephone. Further, the DCO operates at a fixed option bus priority and thus can only provide a "picture" of activities from its view of the option bus. Finally, the DCO is an expensive option, costing roughly the same amount as the telephone itself. What is needed is a way for the user to be able to directly monitor and manipulate the telephone control information at the programmable computing device by having all of the telephone control information received at an option slot in an unaltered form. It would also be desirable to allow the user to select the priority of the option on the bus and thus customize the function of the telephone.